Recently, patent foramen ovale (hereinafter referred to as PFO) has been cited as a cardiogenic factor in a stroke and a hemi headache. PFO is a defect in the septum between the two upper (atrial) chambers of the heart. More specifically, PFO is an incomplete closure of the atrial septum so that a flap or valve-like opening exists in the atrial septal wall. It is said that PFO exists in 20 to 30% of adults.
The foramen ovale occurs at a septum secundum (Septum Secundum, hereinafter, referred to as atrial septum) of the heart and the pressure on the left atrium side exceeds the pressure on the right atrium side in the heart on a normal occasion, so that it is occluded by a septum primum (Septum Primum, hereinafter, referred to as foramen ovale valve). But when the pressure on the right atrium side exceeds the pressure on the left atrium side on the occurrence of a strain (for example, when coughing, when holding on) or the like, the foramen ovale valve opens to the left atrium side and blood flows from the right atrium side (venous side) into the left atrium side (arterial side). When a thrombus is included in this blood, the thrombus is shifted from the venous side to the arterial side, flows along a route involving left atrium→left ventricle→aorta→brain, and can become a factor in a stroke, hemi headache or the like.
To treat PFO, the use of a percutaneous catheter procedure is considered desirable if the same effect as open heart surgery can be obtained.
A closing technique device using the percutaneous catheter can be used also in case of closing defects such as a congenital atrial septum defect (ASD), a PFO, a ventricular septal defect (VSD) and a patent ductus arteriosus (PDA). A device in the past is a device sandwiching the foramen ovale valve and the atrial septum by using disk-shaped membranes or anchor members for closing the defect and which are indwelled in the body.
A PFO closing device described in WO2004/086944 A2 (Patent Document 1) is a device in which an apparatus is inserted into the foramen ovale from the right atrium toward the left atrium, a foramen ovale valve is pulled to the foramen ovale so as to close it, and the tissue is to be sutured by applying electric energy. The PFO closing device should preferably be able to address a foramen ovale, foramen ovale valve and atrial septum which differ in terms of size (smaller versus larger), thicknesses, shape and the like depending on the individual and according to circumstances.
Japanese Patent Application No. 2006-47636 (Patent Document 2) discloses a PFO closing device in which the foramen ovale valve and the atrial septum are sandwiched by a pair of electrodes, and the tissue is sutured by applying electric energy from both electrodes.